An image forming apparatus is known that is configured to form an image by visualizing an electrostatic latent image formed on a latent image carrier by a developing device using a toner as a developer. In such an image forming apparatus, the toner in the developing device is consumed in the course of image formation. Therefore, to supply the toner to the developing device in the image forming apparatus, use of a toner container as a powder storage container storing the toner is considered. As such a toner container, one is known that has a configuration in which a powder loading port for loading the toner is provided and is plugged by attaching a sealing member thereon (refer to Patent Document 1).